Answer: Cell differentiation can be defined as a process in which the less specified cell is converted into the more specified cell. The cells at the embryonic stages is less specialized and during the process of development it becomes more specialized and this process is regulated by gene expression. The gene expression involves a specific group of genes which is expressed or suppressed, that decides the function of the cell.
A fertilized egg shows a single cell which is non-specialized that will become complex and will turn into a multicellular organism by cell differentiation.
This is the reason the adult rabbit looks so different from the single fertilized egg.
